Method And System For Displaying EEG Data

ABSTRACT

A method and system for displaying EEG data is disclosed herein. A plurality of epochs are stitched together with an overlapping section in order to present a continuous EEG recording. Artifact reduction is performed on the epochs and then the epochs are combined together with overlapping sections of preferably two to four seconds.

CROSS REFERENCES TO RELATED APPLICATIONS

The Present Application claims priority to U.S. Provisional PatentApplication No. 61/563,731, filed on Nov. 25, 2011, which is herebyincorporated by reference in its entirety.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not Applicable

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to a method and system fordisplaying EEG data. More specifically, the present invention relates toa method and system for displaying a continuous artifact reduced EEGreport.

2. Description of the Related Art

An electroencephalogram (“EEG”) is a diagnostic tool that measures andrecords the electrical activity of a person's brain in order to evaluatecerebral functions. Multiple electrodes are attached to a person's headand connected to a machine by wires. The machine amplifies the signalsand records the electrical activity of a person's brain. The electricalactivity is produced by the summation of neural activity across aplurality of neurons. These neurons generate small electric voltagefields. The aggregate of these electric voltage fields create anelectrical reading which electrodes on the person's head are able todetect and record. An EEG is a superposition of multiple simplersignals. In a normal adult, the amplitude of an EEG signal typicallyranges from 1 micro-Volt to 100 micro-Volts, and the EEG signal isapproximately 10 to 20 milli-Volts when measured with subduralelectrodes. The monitoring of the amplitude and temporal dynamics of theelectrical signals provides information about the underlying neuralactivity and medical conditions of the person.

An EEG is performed to: diagnose epilepsy; verify problems with loss ofconsciousness or dementia; verify brain activity for a person in a coma;study sleep disorders, monitor brain activity during surgery, andadditional physical problems.

Multiple electrodes (typically 17-21, however there are standardpositions for at least 70) are attached to a person's head during anEEG. The electrodes are referenced by the position of the electrode inrelation to a lobe or area of a person's brain. The references are asfollows: F=frontal; Fp=frontopolar; T=temporal; C=central; P=parietal;O=occipital; and A=auricular (ear electrode). Numerals are used tofurther narrow the position and “z” points relate to electrode sites inthe midline of a person's head. An electrocardiogram (“EKG”) may alsoappear on an EEG display.

The EEG records brain waves from different amplifiers using variouscombinations of electrodes called montages. Montages are generallycreated to provide a clear picture of the spatial distribution of theEEG across the cortex. A montage is an electrical map obtained from aspatial array of recording electrodes and preferably refers to aparticular combination of electrodes examined at a particular point intime.

In bipolar montages, consecutive pairs of electrodes are linked byconnecting the electrode input 2 of one channel to input 1 of thesubsequent channel, so that adjacent channels have one electrode incommon. The bipolar chains of electrodes may be connected going fromfront to back (longitudinal) or from left to right (transverse). In abipolar montage signals between two active electrode sites are comparedresulting in the difference in activity recorded. Another type ofmontage is the referential montage or monopolar montage. In areferential montage, various electrodes are connected to input 1 of eachamplifier and a reference electrode is connected to input 2 of eachamplifier. In a reference montage, signals are collected at an activeelectrode site and compared to a common reference electrode.

Reference montages are good for determining the true amplitude andmorphology of a waveform. For temporal electrodes, CZ is usually a goodscalp reference.

Being able to locate the origin of electrical activity (“localization”)is critical to being able to analyze the EEG. Localization of normal orabnormal brain waves in bipolar montages is usually accomplished byidentifying “phase reversal,” a deflection of the two channels within achain pointing to opposite directions. In a referential montage, allchannels may show deflections in the same direction. If the electricalactivity at the active electrodes is positive when compared to theactivity at the reference electrode, the deflection will be downward.Electrodes where the electrical activity is the same as at the referenceelectrode will not show any deflection. In general, the electrode withthe largest upward deflection represents the maximum negative activityin a referential montage.

Some patterns indicate a tendency toward seizures in a person. Aphysician may refer to these waves as “epileptiform abnormalities” or“epilepsy waves.” These include spikes, sharp waves, and spike-and-wavedischarges. Spikes and sharp waves in a specific area of the brain, suchas the left temporal lobe, indicate that partial seizures might possiblycome from that area. Primary generalized epilepsy, on the other hand, issuggested by spike-and-wave discharges that are widely spread over bothhemispheres of the brain, especially if they begin in both hemispheresat the same time.

There are several types of brain waves: alpha waves, beta waves, deltawave, theta waves and gamma waves. Alpha waves have a frequency of 8 to12 Hertz (“Hz”). Alpha waves are normally found when a person is relaxedor in a waking state when a person's eyes are closed but the person ismentally alert. Alpha waves cease when a person's eyes are open or theperson is concentrating. Beta waves have a frequency of 13 Hz to 30 Hz.Beta waves are normally found when a person is alert, thinking,agitated, or has taken high doses of certain medicines. Delta waves havea frequency of less than 3 Hz. Delta waves are normally found only whena person is asleep (non-REM or dreamless sleep) or the person is a youngchild. Theta waves have a frequency of 4 Hz to 7 Hz. Theta waves arenormally found only when the person is asleep (dream or REM sleep) orthe person is a young child. Gamma waves have a frequency of 30 Hz to100 Hz. Gamma waves are normally found during higher mental activity andmotor functions.

The following definitions are used herein.

“Amplitude” refers to the vertical distance measured from the trough tothe maximal peak (negative or positive). It expresses information aboutthe size of the neuron population and its activation synchrony duringthe component generation.

The term “analogue to digital conversion” refers to when an analoguesignal is converted into a digital signal which can then be stored in acomputer for further processing. Analogue signals are “real world”signals (e.g., physiological signals such as electroencephalogram,electrocardiogram or electrooculogram). In order for them to be storedand manipulated by a computer, these signals must be converted into adiscrete digital form the computer can understand.

“Artifacts” are electrical signals detected along the scalp by an EEG,but that originate from non-cerebral origin. There are patient relatedartifacts (e.g., movement, sweating, ECG, eye movements) and technicalartifacts (50/60 Hz artifact, cable movements, electrode paste-related).

The term “differential amplifier” refers to the key toelectrophysiological equipment. It magnifies the difference between twoinputs (one amplifier per pair of electrodes).

“Duration” is the time interval from the beginning of the voltage changeto its return to the baseline. It is also a measurement of thesynchronous activation of neurons involved in the component generation.

“Electrode” refers to a conductor used to establish electrical contactwith a nonmetallic part of a circuit. EEG electrodes are small metaldiscs usually made of stainless steel, tin, gold or silver covered witha silver chloride coating. They are placed on the scalp in specialpositions.

“Electrode gel” acts as a malleable extension of the electrode, so thatthe movement of the electrodes leads is less likely to produceartifacts. The gel maximizes skin contact and allows for alow-resistance recording through the skin.

The term “electrode positioning” (10/20 system) refers to thestandardized placement of scalp electrodes for a classical EEGrecording. The essence of this system is the distance in percentages ofthe 10/20 range between Nasion-Inion and fixed points. These points aremarked as the Frontal pole (Fp), Central (C), Parietal (P), occipital(O), and Temporal (T). The midline electrodes are marked with asubscript z, which stands for zero. The odd numbers are used assubscript for points over the left hemisphere, and even numbers over theright “Electroencephalogram” or “EEG” refers to the tracing of brainwaves, by recording the electrical activity of the brain from the scalp,made by an electroencephalograph.

“Electroencephalograph” refers to an apparatus for detecting andrecording brain waves (also called encephalograph).

“Epileptiform” refers to resembling that of epilepsy.

“Filtering” refers to a process that removes unwanted frequencies from asignal.

“Filters” are devices that alter the frequency composition of thesignal.

“Montage” means the placement of the electrodes. The EEG can bemonitored with either a bipolar montage or a referential one. Bipolarmeans that there are two electrodes per one channel, so there is areference electrode for each channel. The referential montage means thatthere is a common reference electrode for all the channels.

“Morphology” refers to the shape of the waveform. The shape of a wave oran EEG pattern is determined by the frequencies that combine to make upthe waveform and by their phase and voltage relationships. Wave patternscan be described as being: “Monomorphic”. Distinct EEG activityappearing to be composed of one dominant activity. “Polymorphic”.distinct EEG activity composed of multiple frequencies that combine toform a complex waveform. “Sinusoidal”. Waves resembling sine waves.Monomorphic activity usually is sinusoidal. “Transient”. An isolatedwave or pattern that is distinctly different from background activity.

“Spike” refers to a transient with a pointed peak and a duration from 20to under 70 msec.

The term “sharp wave” refers to a transient with a pointed peak andduration of 70-200 msec.

The term “neural network algorithms” refers to algorithms that identifysharp transients that have a high probability of being epileptiformabnormalities.

“Noise” refers to any unwanted signal that modifies the desired signal.It can have multiple sources.

“Periodicity” refers to the distribution of patterns or elements in time(e.g., the appearance of a particular EEG activity at more or lessregular intervals). The activity may be generalized, focal orlateralized.

An EEG epoch is an amplitude of a EEG signal as a function of time andfrequency.

Various techniques have been developed to present the EEG data to aphysician or technician. However, these techniques are still lacking Ifthe raw EEG report is presented to a physician or technician, thenartifacts typically render the EEG report incapable of distinguishingbrain activity such as a seizure from artifacts. Despite the use ofartifact reduction algorithms, the failure to accurately distinguishtrue physiological rhythmicity from the artifacts is a seriousshortcoming of current software systems and requires an expertassessment. What is needed is a way for a physician or technician toclearly compare the raw EEG report with a filtered report in order tobetter analyze the patient's brain activity. Visually inspecting a rawEEG and then reviewing a processed EEG is difficult since the y-axis andX-axis can be misplaced due to various processing techniques such asstitching. Further, channels may be overlapped adding to furtherdifficulty in reading an EEG.

BRIEF SUMMARY OF THE INVENTION

The present invention provides an EEG system and method that overlays aprocessed EEG report over a raw EEG report to permit a physician ortechnician to clearly see the activity reported.

The present invention provides the ability to select short overlappingepochs where the results of artifact removal from each epoch is stitchedtogether with the result from the next and previous epoch. Thisstitching can be accomplished many ways, but in a preferred method thesignals from the two epochs are combined using a weighted average wherethe weight is proportional to the ratio of the distance to the epochcenters.

For example an epoch length of two seconds is selected with an increment(epoch step) of one second. Artifact removal using BSS and othertechniques is performed on a set of channels for seconds one and twoproducing a two second length “clean” result. Then artifact removal isperformed on seconds two and three producing an overlapping cleanresult. The results overlap in the second second of the record. For eachchannel, the weighted average of the two overlapping results produces afinal result without discontinuities. In the portion of the secondnearer the center of the first epoch the value from the first epoch isweighted higher, and likewise for the portion nearer the center of thesecond epoch. Those skilled in the pertinent art will recognize thatdifferent or variable epoch lengths or steps may be selected whilemoving through the record. Also a different stitching technique might beused.

One aspect of the present invention is a method for filtering artifactsfrom an EEG signal. The method includes generating an EEG signal from amachine comprising a plurality of electrodes, an amplifier andprocessor. The method also includes transforming the EEG signal from aset of channels into a plurality of epochs. Each of the plurality ofepochs has an epoch duration length of less than or equal to two secondsand an increment of less than or equal to one second. The method alsoincludes filtering artifacts from each of the plurality of epochs usinga blind source separation algorithm to generate a plurality of cleanepochs. The method also includes combining the plurality of clean epochsto generate a processed EEG recording.

Yet another aspect of the present invention is a method for filteringartifacts from an EEG signal using a blind source separation algorithm.The method includes generating an EEG signal from a machine comprising aplurality of electrodes, an amplifier and processor. The method alsoincludes transforming the EEG signal from a set of channels into aplurality of epochs. The method also includes filtering artifacts fromeach of the plurality of epochs using a blind source separationalgorithm to generate a plurality of clean epochs. The method alsoincludes combining the plurality of clean epochs to generate a processedEEG recording.

Yet another aspect of the present invention is a system for filteringartifacts from an EEG signal. The system includes electrodes, anamplifier, a processor and a display. The electrodes generate EEGsignals. The amplifier is connected to each of the electrodes by wiresand amplifies the EEG signals. The processor is connected to theamplifier to generate an EEG recording from the EEG signals. The displayis connected to the processor to display an EEG recording. The processoris configured to transform each of the plurality of EEG signals from aset of channels into a plurality of epochs, remove artifacts from eachof the plurality of epochs using a blind source separation algorithm togenerate a plurality of clean epochs, and combine the plurality of cleanepochs to generate a processed EEG recording for display.

Yet another aspect of the present invention is a method for filteringartifacts from an EEG signal using a artifact removal algorithm. Themethod includes generating an EEG signal from a machine comprising aplurality of electrodes, an amplifier and processor. The method alsoincludes transforming the EEG signal from a set of channels into aplurality of epochs. The method also includes filtering artifacts fromeach of the plurality of epochs using an artifact removal algorithm togenerate a plurality of clean epochs. The method also includes combiningthe plurality of clean epochs to generate a processed EEG recording.

Yet another aspect of the present invention is a method for filteringartifacts from an EEG signal by selecting an epoch time and increment.The method includes generating an EEG signal for a patient from amachine comprising a plurality of electrodes attached to the patient, anamplifier and processor. The method also includes selecting an epochtime length and an epoch time increment. The method also includesfiltering artifacts for each of a plurality of epochs using an artifactremoval algorithm to generate a plurality of clean epochs. The methodalso includes assigning a weighted average to each of the plurality ofclean epochs. The method also includes combining the plurality of cleanepochs to overlap to generate a processed EEG recording withoutdiscontinuities.

Yet another aspect of the present invention is a system for filteringartifacts from an EEG signal. The system includes electrodes, aprocessor, and a display. The electrodes generate EEG signals. Theprocessor is connected to the electrodes to generate an EEG recordingfrom the EEG signals. The display is connected to the processor anddisplays an EEG recording. The processor is configured to select anepoch time length and an epoch time increment, filter artifacts for eachof a plurality of epochs using an artifact removal algorithm to generatea plurality of clean epochs, assign a weighted average to each of theplurality of clean epochs, and combine the plurality of clean epochs tooverlap to generate a processed EEG recording without discontinuities.

Having briefly described the present invention, the above and furtherobjects, features and advantages thereof will be recognized by thoseskilled in the pertinent art from the following detailed description ofthe invention when taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is an illustration of a portion of a raw EEG report havingnineteen channels.

FIG. 1A is an enlargement of circle 1A of FIG. 1.

FIG. 2 is an illustration of a portion of a processed EEG report havingnineteen channels in which epochs do not overlap.

FIG. 2A is an enlargement of circle 2A of FIG. 2.

FIG. 3 is an illustration of a portion of a processed continuous EEGreport in which sections of the epochs of the EEG report are stitched tooverlap.

FIG. 3A is an enlargement of circle 3A of FIG. 3.

FIG. 4 is an illustration of a portion of processed continuous EEGreport in which sections of the epochs of the EEG report are stitched tooverlap.

FIG. 5 is a flow chart of a method for displaying EEG data.

FIG. 6 is a flow chart for a method of artifact reduction.

FIG. 7 is an illustration of an EEG system used on a patient.

FIG. 8 is a map representing the international 10-20 electrode systemfor electrode placement for an EEG.

FIG. 9 is a detailed map representing the intermediate 10% electrodepositions, as standardized by the American ElectroencephalographicSociety, for electrode placement for an EEG.

FIG. 10 is a block diagram of an EEG machine component of an EEG system.

FIG. 11 is an illustration of isolated adjacent epochs.

FIG. 12 is an illustration of isolated adjacent epochs.

FIG. 13 is an illustration of epochs stitched together with anoverlapping portion.

FIG. 14 is an example of prior art combining of epochs resulting indiscontinuous or missing information from the processed and stitched EEGrecording.

DETAILED DESCRIPTION OF THE INVENTION

A raw or original EEG report 100 is shown in FIG. 1. The original EEGreport 100 has a plurality of channels FP1-Ref through to O2-Ref, shownat the Y axis 105 of the report. The X-axis of the report is time. Theoriginal EEG report 100 has not been subjected to artifact reduction.The original EEG report contains artifacts from various sources such asmuscle movement, eye movement, sweating, electrode cables and the like.However, the EEG may also have certain activity that a physician ortechnician is looking for from the EEG report in order to accuratelyanalyze the patient's brain activity. For example, the activity shown inFIG. 1A at a time 655.000 may represent a certain stage of brainactivity for the patient that is important to the physician ortechnician. However, normally, the physician or technician will notreview the raw EEG report 100 due to the presence of artifacts.

FIG. 2 is an illustration of a processed EEG report 200 of the originalEEG report 100 of FIG. 1 that has undergone artifact reduction and thestitching of epochs in order to recreate the EEG report, however, theepochs do not overlap resulting in lost information and/ordiscontinuities. The processed EEG report 200 has a plurality ofchannels FP1-Ref through to O2-Ref, shown at the Y axis 205 of thereport. The X-axis of the report is time. As shown in FIG. 2A, theprocessed EEG report 200 at time 655.000 is quite different inappearance than the original EEG report 100 at time 655.000. Thisprimarily due to stitching of epochs to recreate the EEG report, howeverif a physician or technician was only looking at the processed EEGreport 200, the physician or technician would not be aware of the trueactivity at time 655.000.

FIG. 3 is an illustration of a processed continuous EEG report 300 ofthe original EEG report 100 of FIG. 1 that has undergone artifactreduction and the stitching of overlapping epochs in order to recreatethe EEG report. The processed EEG report 300 has a plurality of channelsFP1-Ref through to O2-Ref, shown at the Y axis 305 of the report. TheX-axis of the report is time. As shown in FIG. 3A, the processed EEGreport 300 at time 655.000 is more similar in appearance to the originalEEG report 100 at time 655.000 than the processed EEG report 200 of FIG.2. However, there is still difficulty in analyzing a patient's brainactivity by switching back and forth from an original EEG report 100 toa processed EEG report 200 or a processed continuous EEG report 300.

FIG. 4 is an illustration of an EEG report 400, based on the EEG report300 of FIG. 3, in which channels have been removed for a clearerillustration of channels. The illustration of the combined EEG report400 only has five channels in order to clearly illustrate the invention,however, those skilled in the pertinent will recognize that the combinedEEG report 400 could have sixteen, twenty, twenty-seven and any numberof channels without departing from the scope and spirit of the presentinvention.

A flow chart for a method 500 for displaying EEG data is shown in FIG.5. At block 501, an original EEG report is generated from an EEG signal.The original EEG report is generated from an EEG machine comprising aplurality of electrodes and processor. The original EEG report comprisesa first plurality of channels. At block 502, the original EEG signal ispartitioned from a set of channels into epochs of which each has apredetermined duration length and an overlap increment. At block 503,artifact reduction is performed on the epochs to generate artifactreduced epochs. At block 504, the artifact reduced epochs are combinedwith overlapping adjacent epochs for a continuous EEG recording togenerate a processed continuous EEG report. The stitched, overlappingepochs and continuous processed EEG report is displayed on a displayscreen, preferably a monitor. The stitched, overlapping epochs andcontinuous processed EEG report is not missing timeframes from stitchingor creating discontinuities in the EEG report which is read by aphysician or technician. All of the brain activity remains since theepochs overlap. The brain activity is preferably spikes, sharp waves,spike and wave discharges, artifacts, and the like

FIG. 6 is a flow chart of a preferred method 600 for displaying EEGdata. At block 601, an original EEG report is generated from an EEGsignal for a patient from a machine preferably comprising electrodesattached to the patient, an amplifier and processor. At block 602, theoriginal EEG signal is partitioned from a set of channels into aplurality of epochs. Each of the plurality of epochs having an epochduration length and an overlap increment. At block 603, a first artifactreduction is performed on the plurality of epochs to remove electrodeartifacts. At block 604, a second artifact reduction is performed on theplurality of epochs to remove muscle artifacts. At block 605, a thirdartifact reduction is performed on the plurality of epochs to remove eyemovement artifacts. At block 606, the plurality of epochs are combinedto overlap wherein each epoch of the plurality of epochs overlaps anadjacent epoch to form a processed continuous EEG report. At block 607,a processed continuous EEG recording is generated from the combinedepochs.

Each of the plurality of epochs preferably has an epoch duration lengthof two seconds and an increment of one second. Alternatively, each ofthe plurality of epochs has an epoch duration length of four seconds andan increment of two seconds. The artifact removal algorithm ispreferably a blind source separation algorithm. The blind sourceseparation algorithm is preferably a CCA algorithm or an ICA algorithm.The clean epochs are preferably combined using a weighted average andthe weight of the weighted average is preferably proportional to theratio of the distance to an epoch center.

As shown in FIG. 7, an EEG system is generally designated 20. The systempreferably includes a patient component 30, an EEG machine component 40and a display component 50. The patient component 30 includes aplurality of electrodes 35 a, 35 b, 35 c attached to the patient 15 andwired by cables 38 to the EEG machine component 40. The EEG machinecomponent 40 comprises a CPU 41 and an amplifier component 42. The EEGmachine component 40 is connected to the display component 50 fordisplay of the combined EEG reports, and for switching from a processedEEG report to the combined EEG reports, or from the processed EEG reportto an original EEG report. As shown in FIG. 10, the EEG machinecomponent 40 preferably includes a stitching engine 45, an artifactreduction engine 46, an overlay engine 47, a memory 41, a memorycontroller 42, a microprocessor 43, a DRAM 44, and an Input/Output 48.Those skilled in the pertinent art will recognize that the machinecomponent 40 may include other components without departing from thescope and spirit of the present invention.

A patient has a plurality of electrodes attached to the patient's headwith wires from the electrodes connected to an amplifier for amplifyingthe signal to a processor which is used to analyze the signals from theelectrodes and create an EEG recording. The brain produces differentsignals at different points on a patient's head. Multiple electrodes arepositioned on a patient's head as shown in FIGS. 8 and 9. For exampleFp1 on FIG. 8 is represented in channel FP1-Ref on FIG. 4. The number ofelectrodes determines the number of channels for an EEG. A greaternumber of channels produces a more detailed representation of apatient's brain activity. Preferably, each amplifier of an EEG machinecomponent 40 corresponds to two electrodes attached to a patient's head.The output from an EEG machine component is the difference in electricalactivity detected by the two electrodes. The placement of each electrodeis critical for an EEG report since the closer electrode pairs are toeach other, the less difference in the brainwaves that are recorded bythe EEG machine component. A more thorough description of an electrodeutilized with the present invention is detailed in Wilson et al., U.S.Pat. No. 8,112,141 for a Method And Device For Quick Press On EEGElectrode, which is hereby incorporated by reference in its entirety.The EEG is optimized for automated artifact filtering. The EEGrecordings are then processed using neural network algorithms togenerate a processed EEG recording which is analyzed for display.

Algorithms for removing artifact from EEG typically use Blind Source

Separation (BSS) algorithms like CCA (canonical correlation analysis)and ICA (Independent Component Analysis) to transform the signals from aset of channels into a set of component waves or “sources.” The sourcesthat are judged as containing artifact are removed and the rest of thesources are reassembled into the channel set.

FIG. 11 is an isolated view of adjacent unprocessed epochs 1101 and1102. Epoch 1101 has an overlapping portion 1103 and epoch 1102 has anoverlapping portion 1104. In this example, the overlapping portions 1103and 1104 are approximately two seconds in length. Thus, overlappingportions 1103 and 1104 represent the same timeframe (two seconds) forraw EEG recording.

FIG. 12 is an illustration of adjacent processed epochs 1105 and 1106.Artifact reduction has been performed on these epochs 1105 and 1106.Processed epochs 1105 and 1106 represent the same timeframe asunprocessed epochs 1101 and 1102. Thus, epoch 1105 is the result ofartifact reduction of unprocessed epoch 1101, and epoch 1106 is theresult of artifact reduction of unprocessed epoch 1102. Processed epoch1105 has an overlapping portion 1107 and processed epoch 1106 has anoverlapping portion 1108. Thus, overlapping portions 1107 and 1108represent the same timeframe (two seconds) for the processed EEGrecording. Further, overlapping portion 1107 is the same timeframe asoverlapping portion 1103 and overlapping portion 1108 is the sametimeframe as overlapping portion 1104. Further overlapping portions1103, 1104, 1107 and 1108 represent all the same timeframe.

FIG. 13 is an illustration of the stitching of adjacent processed epochs1105 and 1106 into a section of continuous processed EEG recording 1109.Portion 1110 is the overlapping portions 1107 and 1108 from adjacentprocessed epochs 1105 and 1106. As shown, no information is lost, andthe processed EEG recording is continuous, without abrupt terminationpoints where epochs have been stitched together.

FIG. 14 is an illustration of the prior art approach of stitching ofepochs without overlapping portions. The section 1112 of the processedEEG recording has a stitching portion 1111 which has changed from thesame timeframe of the processed epochs 1105 and 1106. The stitchingportion 1111 is different from section 1110 of FIG. 13.

From the foregoing it is believed that those skilled in the pertinentart will recognize the meritorious advancement of this invention andwill readily understand that while the present invention has beendescribed in association with a preferred embodiment thereof, and otherembodiments illustrated in the accompanying drawings, numerous changesmodification and substitutions of equivalents may be made thereinwithout departing from the spirit and scope of this invention which isintended to be unlimited by the foregoing except as may appear in thefollowing appended claim. Therefore, the embodiments of the invention inwhich an exclusive property or privilege is claimed are defined in thefollowing appended claims.

We claim as our invention:
 1. A method for generating an EEG recording,the method comprising: generating an original EEG signal from a machinecomprising a plurality of electrodes, an amplifier and processor;partitioning the original EEG signal from a set of channels into aplurality of epochs, each of the plurality of epochs having an epochduration length and an overlap increment; performing artifact reductionon the plurality of epochs to generate a plurality of artifact reducedepochs; and combining the plurality of artifact reduced epochs togenerate a processed EEG recording, wherein each of the plurality ofartifact reduced epochs overlaps an adjacent epoch to produce acontinuous EEG recording.
 2. The method according to claim 1 wherein theoriginal EEG is subjected to a blind source separation algorithm.
 3. Themethod according to claim 1 wherein the artifact reduction is for atleast one of muscle artifact, eye movement artifact, electricalartifact, heartbeat artifact, tongue movement artifact, and chewingartifact.
 4. The method according to claim 1 wherein the plurality ofartifact reduced epochs are combined using a weighted average.
 5. Themethod according to claim 1 further comprising illustrating theprocessed EEG recording on a display in communication with the processorwherein an operator switches from illustrating the processed EEGrecording to illustrating an unprocessed EEG recording.
 6. The methodaccording to claim 1 wherein each of the plurality of epochs has anepoch duration length of four seconds and an increment of two seconds.7. A system for filtering artifacts from an EEG signal, the systemcomprising: a plurality of electrodes for generating a plurality of EEGsignals; at least one amplifier connected to each of the plurality ofelectrodes by a plurality of wires to amplify each of the plurality ofEEG signals; a processor connected to the amplifier to generate an EEGrecording from the plurality of EEG signals; and a display connected tothe processor for displaying an original EEG recording and a processedEEG recording; wherein the processor is configured to partition theoriginal real-time EEG signal from a set of channels into a plurality ofepochs, each of the plurality of epochs having an epoch duration lengthand an overlap increment, perform artifact reduction on the plurality ofepochs to generate a plurality of artifact reduced epochs, and combinethe plurality of artifact reduced epochs to generate a processedreal-time EEG recording, wherein each of the plurality of artifactreduced epochs overlaps an adjacent epoch to produce a continuous EEGrecording.
 8. The system according to claim 7 wherein each of theplurality of epochs has an epoch duration length of four seconds and anincrement of two seconds.
 9. The system according to claim 7 wherein theartifact reduction is for at least one of muscle artifact, eye movementartifact, electrical artifact, heartbeat artifact, tongue movementartifact, and chewing artifact.
 10. A method for generating a continuousEEG recording from a plurality of artifact reduced epochs, the methodcomprising: generating an original EEG signal for a patient from amachine comprising a plurality of electrodes attached to the patient, anamplifier and processor; partitioning the original EEG signal from a setof channels into a plurality of epochs, each of the plurality of epochshaving an epoch duration length and an overlap increment; performing afirst artifact reduction on the plurality of epochs to remove electrodeartifacts; performing a second artifact reduction on the plurality ofepochs to remove muscle artifacts; performing a third artifact reductionon the plurality of epochs to remove eye movement artifacts; combiningthe plurality of epochs to overlap wherein each epoch of the pluralityof epochs overlaps an adjacent epoch; and generating a processed EEGrecording without discontinuities from the combined plurality of epochs.11. The method according to claim 10 wherein each of the plurality ofepochs has an epoch duration length of two seconds and an increment ofone second.
 12. The method according to claim 10 wherein each of theplurality of epochs has an epoch duration length of four seconds and anincrement of two seconds.